Process for catalyzed abnormal addition reactions



. P tented-x33 r i raocEss non cA'rALYmn ABNORMAL I 1 ADDITIONnnac'rrons Theodore W. Evans,

Oakland, and William E. I Vaughan and Frederick F.

Rust, Berkeley,

v(lalifi, asslgnors to Shell Development Company, San Francisco, Calif acorporationoi Delaware No Drawing. Application June 26, 1944,

- Serial No. 542,242 c 12 Claims. "(01. 204-463) This invention relatesto an improved method for the addition of. hydrogen sulfide and/ormercaptans to symmetrical or unsymmetrical organic compounds containingone or more unsaturated linkages of aliphatic character.v In one of itsmore specific embodiments, the invention pertains to a novel method ofeffecting a controlled reaction between hydrogen sulfide or a mercaptanand unsymmetrical organiccompounds containing at least one unsaturatedlinkage of aliphatic character, i. e. an olefinic or acetylenic bond, toproduce addition products of predetermined character. T

This application is a continuation-in-part of the copending application,Serial No. 432,048, filed February 23, 1942, now Patent No. 2,376,675,dated May 22, 1942.

It is known that mercaptans and thio-ethers. may be produced by reactinghydrogen sulfide or a suitable mercaptanwith an unsaturated organiccompound, e. g. unsaturated hydrocarbon, at elevated temperatures in theapproximate range of from 200 C. to 750 C. -1n some cases such reactionswere effected at superatmospheric pressures. .When hydrogen sulfide isreacted with unsaturated organic compounds under the out-] linedconditions, the sulfhydryl group attaches to the unsaturated carbon atomcontaining the lesser number of hydrogen atoms attached thereto, sothat, as clearly brought out' by Jones and Reid (Journal AmericanChemical Society. vol.- 60, pp. 2452-2455 the" addition takesplaceaccording to Markownikofis rule. Therefore, when compounds, contrary tothe course suggested by the Markownikofi rule, by effectingthe reactionat normal temperatures or even at considerably lower temperatures, underthe deliberate influence of ultraviolet radiations having wavelengths ofbelow about 2900 to 3000 Angstrom units. It is known that the presenceof peroxides or of peroxide-forming compounds in unsaturated organiccompounds, e. g. unsaturated hydrocarbons, is undesirable; The processesinvolving the abnormal addition of hydrogen sulfide and/or of mercaptansto unsaturated organic com-pounds under the deliberate influence ofultraviolet radiations necessitate the use of special equipment which iscapable of transmitting rays of the defined low wavelengths.- In' otherwords, in order to efiectthe desired reaction it is necessary to employreaction vessel and/or lamps of quartz or other suitable materials, e.g. calcium fluoride, which are capable of transmitting the defined shortwavelengths of 2900 to 3000 Angstrom units, and below.

It has now been discovered that unsaturated organic compounds of theclass more fully described hereinbelow may be reacted with hydrogensulfide or mercaptans. to efiect directional addition thereof via theabove-defined abnormal addition, this reaction being effected withoutthe necessity of resorting to high temperatures and/or elevatedpressures, and in the absence of undesirable peroxides-or peroxide-formterminally unsaturated olefins are thus reacted with hydrogen sulfide,the reaction product predominates in secondary mercaptans and/orsecondary thio-ethers. When the unsaturated organic compounds have beenreacted with the mercaptans at the aforementioned elevated temperatures.the sulfur atom of the mercapto radical attached predominantly to theunsaturated carbon atom holding the most hydrogen atoms so that thisaddition was contrary to the course suggested by the Markownikofi rule.This condition was designated-as abnormal addition on the assumptionlike halogen acids. vWith reference to'the addition of mercaptans tounsaturated organic comthat mercaptans should add pounds, it is knownthat the abnormal addition maybe catalyzed by free oxygen, air, ozone,peroxides, ascaridole and the like, while compounds of the type ofhydroquinone and piperidine act as reaction inhibitors.

It has recently been discovered that hydrogen sulfide may be added tounsaturated organic ing compounds. It has also been discovered that thisreaction according to this invention may be effected without thenecessity of employing any 35.

special equipment or apparatus capable of transmittihg very lowultraviolet rays. such as radiations having wavelengths of 2900 to 3000Angstrom units. and below. According to the present process, thisabnormal addition of mercaptans and/or hydrogen sulfide isattained byeffecting the reaction under irradiating conditions (particularly underthe deliberate influence of rays which will not otherwise dissociate anyone of the reactants), and in the presence of certain catalystshaving-definite and specific characteristics which promote the abnormaladdition but the presence of which in the unsaturated organic compoundsis not detrimental. Generally speaking; these catalysts or reactionsensitizers comprise compounds which yield free radicals under thephotochemical conditions employed to effect the addition reaction.

The term free radical. as employed herein,

' refers to an organic compound in which all of the valences are notsaturated (see Hackhs the class more fully described herein' andconsisting of or comprising free radicals of the type definedhereinbelow,- will catalyze and control the reaction between anunsaturated organic compound and a mercaptan or hydrogen sulfide so thatthe reaction will occur via the so-called "abnormal" addition atordinary or even subnormal temperatures and without the necessity ofemploying special equipment or apparatus which will transmitultraviolet. radiations having wavelengths 01' 2900 to 3000 Angstromunits, or below.

Broadly stated, the present invention resides in a photochemical processof effecting the addition of suitable mercaptans or hydrogen sulfide inthe presence of metallo-hydrocarbon compounds and under the deliberateinfluence of light capable of photochemically dissociating said catalystor sensitizer, this reaction being effected at normal temperatures, i.e. in the neighborhood 01' from about C. to about 15 C., or even atconsiderably lower temperatures. As stated, this photochemical'addition,according to the present invention, occurs contrary to the coursesuggested by Markownikofl for the addition of hydrogen halides, and inaccordance with the rule proposed by Posner (Berichta'vol. 38, p. 646(1904)) concerning the addition of mercaptans todouble bonds.

The unsaturated organic compounds which may be treated according to theprocess of this invention include hydrocarbons containing one or moreplefinic and/or acetylene linkages.- Examples of such hydrocarbons areethylene, propylene, butene-l, butene-Z, isobutylene,pentene-1,'pentene-2, hexene-J, 4-methyl-pentene-1, 4,4 dimethyl-pentene-l,4-methyl-pentene-2, octene- 1, decene-l, cetene-l, styrene, cyclohexene,3- methyl-cyclohexene, 1,4-diphenyl-butene-2, bu-

'tadiene-1,3, pentadiene-L3, pentadiene-l/i, hexadiene-l,5,hexadiene-lgt', acetylene, propyne,

" methallyl halides, and the like. Other examples ofsubstitutedunsaturated hydrocarbons are methyl acrylate, methyl methacrylate,

. 4 pounds, via abnormal addition, to producecompounds in which bothterininal carbon atoms have sulfhydryl or mercapto radicals attachedthereto. Another group of organic compounds which may be employed as theprimary material comprises or includes organic compounds wherein anolefinic linkage is in non-terminal position between two carbon atomshaving a dissimilar number of hydrogen atoms attached to each of saidunsaturated carbon atoms due, for example, to various substituentsattached thereto. For instance, the double bond may be between twocarbon atoms which are of secondary and tertiary character,respectively. Another example is a compound in which the unsaturatedcarbon atoms are both primary or both secondary, but have unequalnumbers of halogen atoms, such as chlorine, bromine, fluorine and/oriodine atoms attached to them.

Any sufliciently stable mercaptan is suitable as a reactant to beemployed in the photochemical addition thereof to the above-definedclass of unsaturated organic compounds. A suitable mercaptan may containone or more sulfhydryl groups or radicals, and be of alkyl, aralkyl, a1-kenyl, arallrenyl or aryl character. The mercapto radical may be linkedto an aliphatic or an aromatic carbon atom. In the majority of cases itis preferable to employ the normal or iso alkyl chain mercaptans ofprimary, secondary or tertiary character, particularly those containedin or derived from petroleum and petro leum products. The methyl, ethyl,butyl, amyl, "hexyl, heptyl, octyl and the like mercaptans, as well astheir homologues, analogues and substitution products, may be employedwith excellent results. Another group of mercaptans which may beemployed as one of the two reactants comprises or includes thedimercaptans, and pari5 ing a high molecular weight.

ticularly the polymethylene dimercaptans of the general formulaHS(CH2)nSH. This group of mercaptans may be reacted with, for example,aliphatic hydrocarbons containing a plurality of unsaturated linkages toproduce thio-ethers hav- Of the metallo-hydrocarbon compounds which maybe used to promotethe abnormal addition "butyne-l, pentyne-2, hexyne-1,cetyne-l, octyl- The above compounds, and their 'For instance, theunsaturates may 65 reaction in accordance with the process of thepresent invention, it is preferable to use those which may be readilydissociated by light. out any intention of being limited'by thecompounds enumerated herein, it may be stated that representativecompounds of this class or group include substances of the type oftetraethyl lead, tetramethyl lead, tetraphenyl lead, tetraethyl tin,dimethyl-diethyl tin, tetramethyl tin, mi

methyl-ethyl tin, tetraethyl germanium, diphenyl germanium, diandtrivalent organo-tin compounds of both the aliphatic and aromaticseries,

as triphenyl tin anddiethyl tin, organo-lead comdivinyl ether, diallylether, dimethallyl ether,

in terminal or alpha position. Also, aliphatic 1o hydrocarbons andtheir'various-substituted derivatives, e. g. halosubstitutedderivatives, containing unsaturated linkages both in alpha and omegapositions (1. e. terminal pdsitions), may

be readily reacted with the above-outlined compounds containing diandtrivalent lead, and the like, their homologues and analogues. Althoughthe above organo-metallic or metallo-hydrocarbon compounds coversubstances in which a carbon atom of the organic radical is uniteddirectly to a metal'at m of the fourth group of the periodic table, itis to be understood that organo-metallic compounds containing metals ofother groups are also suitable catalysts. Thus, dimethyl cadmium,dipropyl cadmium, diethyl mercury, trimethyl lanthalum, trimethyl bismuth, triphenyl bismuth, tetraphenyl chromium hexaphenyl disilane, andsimilar compounds may be employed as the catalysts which will cause 78the abnormal addition of mercaptans or hydrogen Withsystem. Since theabnormal addition reaction occurs photochemically, or under theinfluence of catalysts or sensitizers which are dissociated to produceradicals which initiate the reaction, no heating is necessary. In fact,in many instances the reaction, although it may be realized attemperatures of about 25 C., is preferably effected at temperatureswhich are even below C. Also. it was discovered that the abnormaladdition of mercaptanscr hydrogen sulfide, when the reaction is effectedunder the influence of the abovedefined class ofcatalysts orsensitizers, proceeds regardless of the presence or absence of a liquidfilm in the reaction zone. Although the reaction described herein may bepromoted or effected by using the whole range of ultraviolet radiations,it has been pointed out above that the presence of the defined catalystsor sensitizers (which, incidentally, do not have a deterimental efl'ecton the reactants) eliminates the necessity of using radiations havingvery short wavelengths. In other .words, whereas abnormal addition of,for example,

hydrogen sulfide to an unsaturated organic compound would requireultraviolet radiations having wavelengths of below about 2900 to 3000Angstrom units, the addition of even small amounts, e. g. from about 1%to about 10%, of a compound of the class of catalysts or sensitizersdefined above permits effective addition even when the radiations havelonger wavelengths, provided such rays will cause the initialdissociation of the catalyst or sensitizer, so that the free radicalsthus formed may initiate the chain mechanism and at the same timecontrol the reaction to effect "abnornal" addition. For example, in thecase of tetraethyl lead, this catalyst-may be dissociated by light ofabout 3600 Angstrom units, which is ordinarily inefiective in initiatingthe reaction.

The abnormal reaction according to the present process may be effectedin a batch, intermittent or continuous manner. When the process isexecutedbatchwise, the reactants, together with a suitable amount of thecatalyst or sensitizer of the defined class, may be conveyed under anysuitable or opt um pressure and temperature into a suitable containerwhich is then illuminate'd, preferably with ultraviolet light, for aperiod of time sufllcient to effect the desired additionreaction.Although containers of quar'tz'cr the like may belemplcyed, so as topermit light waves of between 2900 and 3000 Angstrom units therethrough,it is possible to employ ordinary glass or Pyrex glass, sincewavelengths passing through this type of glass will also dissociate thesensitizer or catalyst and thus initiate and efiect the desiredreaction.

Although there is no intention of being limited by any details therein,the following illustrative examples represent specific embodiments ofthe present invention.

Example I Propylene and hydrogen sulfide were introduced in the liquidstate and in equal Volumetric proportions into a Pyrex glass reactor.The reaction vessel was then sealed and illuminated for a period ofabout six minutes by radiations emanating from a mercury quartz lamp.The reactor was maintained at a temperature of about 0 C. An analysis ofthe contents from the reactor showed that only about 4% of thepropylenereacted.

Example I! The experiment described inExample I was repeated. However,prior to the' sealing of the reactor, tetraethyl lead was added in suchan amount that. the volumetric ratio of propylene, hydrogen sulfide andtetraethyl lead in the reactor was 7.4:7.4:1. After the six-minuteillumination the reaction mixture was distilled to evapcrate theunreacted compounds. It was then found that about 75% of the propylenereacted via abnormal addition, the reaction product consisting of about80 weight percent of n-propyl mercaptan and about 20 weight percent ofdi-n- I propyl sulfide.

Example 111 Ewamplc IV Propylene, hydrogen-sulfide and tetraphenyl leadare introduced into a Pyrex glass container in such amounts that theliquid volumetric ratio of said ingredients is l2:l2:1. The illuminationof the mixture at a temperature of about 25 C. with ultravioletradiations from a quartz mercury lamp results in the formation ofsubstantial amounts of n-propyl mercaptan and some di-np pyl sulfide.

Substantially the same results' are obtained when diethyl mercury isemployed in lieu of tetraphenyl lead as the catalyst or sensitizer.

Example V When hexene-l is reacted with hydrogen sulfide in the presenceof a minor amount of tetraethyl lead in accordance with the processdescribed in Example II, the, reaction product contains n-hexylmercaptan and di-n-hexyl sulfide.

The yield of the desired products of the abnormal addition depend inpart on the amount of 7 catalyst employed and the time during which thereactants and the catalyst are subjected to the illumination,

We claim as our invention: Y

1. In a process of reacting propylene with hydrogen sulfide to formproducts of addition, the

improvement which'ccmprises directly controlling the reacticn-to producepredominantly normal prcpyl mercaptan by adding a minor amount oftetraethyl lead to .the reactants and subjecting the mixture, at atemperature'not in excess of about 25 0., .to the action ofphotochemical radiations above 3000 Angstrom units but capable 7Angstrom units but capable of dissociating tetraethyl lead.

3. In a proces of efiecting abnormal addition of hydrogen sulfide, thesteps of mixing an aliphatic hydrocarbon containing an alpha unsaturatedlinkage with hydrogen sulfide and tetraethyl lead and effecting thereaction at a temperature not' in excess of about 25 C. and under theinfluence of photochemical radiations above 3000 Angstrom units butcapable of dissociating tetraethyl lead.

4. In a process of effecting abnormal addition of hydrogen sulfide, thesteps of mixing an alphaunsaturated hydrocarbon with hydrogen sulfideand tetraethyl lead and effecting the reaction photochemically under theinfluence of photochemical radiations above 3000 Angstrom units butcapable of dissociating tetraethyl lead.

5. The process according to claim 4 wherein te-traethyl lead is employedin an amount of from about 1% to about of the total mixture sub jectedto reaction.

6. In a'process of effecting abnormal addition of hydrogen sulfide, thesteps of mixing an alphaunsaturated hydrocarbon with hydrogen sulfideand a metallo-hydrocarbon compound in which a carbon atom of thehydrocarbon radical is united directly to a metal of the fourth group ofthe periodic table which metallo-hydrocarbon is decomposed byphotochemical radiations above 3000 Angstrom units, and eirecting thereaction photochemically under the influence of photo-.

chemical radiations above 3000 Angstrom units but capable ofdissociating the metallo-hydrocarbon compound.

7. In a process of producing abnormal addition of hydrogen sulfide, .thestep of reacting an unsaturated organic compound containing anunsaturated linkage between two carbon atoms having a dissimilar numberof hydrogen atoms attached .to each of said unsaturated carbon atomswith hydrogen sulfidein the presence of a metallo-hydrocarbon compoundin which a carbon atom of the hydrocarbon radical is united directly toa metal of the fourth group of the periodic table whichmetallo-hydrocarbon is decomposed by photochemical radiations above 3000Angstrom units and under the deliberate influence of photochemicalradiations above 3000 Angstronr'units but capable of dissociating saidmetallo-hydrocarbon compound.

8. In a process of producing di-normal propyl thio-ether, the steps ofmixing propylene with normal propyl mercantan and tetraethyl lead andefiecting the reaction in the liquid state at a temperature of belowabout C. and under the deliberate influence of photochemical radiationsabove 3000 Angstrom units but capable of dissociating tetraethyl lead. i

9; In a processof producing thio-ethers, the steps of contacting analiphatic hydrocarbon containing an alpha-unsaturated linkage with amercaptan and subjecting said mixture in the liquid state at atemperature of below about 25 C. and in the presence of ametallo-hydrometallo-hydrocarbon is decomposed by photo-.

carbon compound in which a carbon atom of the hydrocarbon radical isunited directly to a metal of the fourth group of the periodic tablewhich metallo-hydrocarbon is decomposed by photochemical radiationsabove 3000 Angstrom units to the influence of photochemical radiationsabove 3000 Angstrom units but capable of decomposing saidmetallo-hydrocarbon compound.

10. In a .process of producing thio-ethers, the steps of contacting anunsaturated hydrocarbon having at least one unsaturated linkage betweentwo carbon atoms having a dissimilar number of hydrogen atoms attachedthereto with a mercaptan, maintaining the reactants at a temperature notin excess of about 25 C. and in the absence of peroxides, and subjectingthe reactants in .the presence of a metallo-hydrocarbon'compound inwhich a carbon atom of the hydrocarbon radical is united directly to ametal of the fourth group of the periodic table whichmetallo-hydrocarbon is decomposed by photochemical radiations above 3000Angstrom units to the influence of photochemical radiations of above3000 Angstrom units but capable of decomposing the, metallohydrocarboncompound under the operating conditions.

11. In a process of eifecting reactions via abnormal addition, the stepsof reacting an unsaturated hydrocarbon having at least one unsaturatedlinkage between two carbon atoms having a. dissimilar number of hydrogenatoms attached thereto, with a compound selected from the classconsisting of hydrogen sulfide and mercaptans in the presence of ametallo-hydrocarbon compound in which a carbon atom of the hydrocarbonradical is united directly to a metal of the fourth group of theperiodic table which chemical radiations above 3000 Angstrom units, andeffecting the reaction photochemically in the absence of peroxides andunder the deliberate influence of photochemical radiations above 3000Angstrom units but capable-of decomposing said metallo-hydrocarboncompounds.

12. Ina process for effecting reactions via abnormal addition, the stepsof reacting an-unsaturated organic compound containing an unsaturatedlinkage between two carbon atoms having a dissimilar number of hydrogenatoms attached thereto, with a compound selected from the classconsisting of hydrogen sulfide and mercaptans in the presence of a.metallo-hydrocarbon compound in which a carbon atom of the hydrocarbonradical is united directly to a metal of the fourth group of theperiodic table which metalluhydrocarbon is decomposed by photochemicalradiations above 3000 Angstrom units, and eflectw ing the reactionphotochemically in the absence of peroxides and under the deliberateinfluence of photochemical radiations above 3000 Angstrom units butcapable of decomposing said metallohydrocarbon compounds.

THEODORE W. EVANS.

WILLIAM E. VAUGHAN.

FREDERICK F. RUST.

